Analgesic and Sedative Effects of Epidural Lidocaine-Xylazine in Elective Bilateral Laparoscopic Ovariectomy in Standing Mule Mares
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animals Article Analgesic and Sedative Effects of Epidural Lidocaine-Xylazine in Elective Bilateral Laparoscopic Ovariectomy in Standing Mule Mares Cecilia Vullo 1,* , Adolfo Maria Tambella 2 , Marina Meligrana 3 and Giuseppe Catone 4 1 Department of Chemical, Biological, Pharmaceutical, and Environmental Sciences (ChiBioFarAm), Via S. D’Alcrontes, 31 University of Messina, 98166 Messina, Italy 2 School of Bioscience and Veterinary Medicine, University of Camerino (MC), Via Circonvallazione 92-93, 62022 Matelica, Italy; [email protected] 3 Veterinary Practitioner, Parghelia (VV), 89900 Vibo Valentia, Italy; [email protected] 4 Department of Veterinary Sciences, University of Messina, Polo Universitario dell’Annunziata, 98168 Messina, Italy; [email protected] * Correspondence: [email protected] Simple Summary: Elective bilateral ovariectomy in mule mares is recommended to correct unde- sirable behaviour effects related to oestrus and also in order to improve work performance. This procedure is usually carried out in a standing position with a combination of sedative and analgesic drugs along with local anaesthesia of the ovarian pedicles. The aim of the study was to evaluate the effects of epidural lidocaine-xylazine in sedated standing mules undergoing elective bilateral laparoscopic ovariectomy. The findings suggest that no significant changes were found in heart rate, respiratory rate, rectal temperature with respect to baseline values. Sedation and analgesia were satisfactory in six out of the eight mules. Epidural analgesia with lidocaine-xylazine may be a good Citation: Vullo, C.; Tambella, A.M.; Meligrana, M.; Catone, G. Analgesic alternative to local anaesthetics infiltration of the ovarian pedicle for elective bilateral laparoscopic and Sedative Effects of Epidural ovariectomy in standing mule mares, but further studies should be performed. Lidocaine-Xylazine in Elective Bilateral Laparoscopic Ovariectomy Abstract: The purpose of this study was to determine the analgesic efficacy and safety of epidu- in Standing Mule Mares. Animals ral lidocaine-xylazine administration in standing mules undergoing elective bilateral laparoscopic 2021, 11, 2419. https://doi.org/ ovariectomy in order to suppress unwanted behaviour. Eight mule mares were sedated with intramus- 10.3390/ani11082419 cular 0.05 mg/kg acepromazine followed by 1.3 mg/kg of xylazine and 0.02 mg/kg of butorphanol intravenously. Sedation was maintained by a constant rate infusion of 0.6 mg/kg/h of xylazine. The Academic Editor: Thijs van Loon paralumbar fossae were infiltrated with 30 mL of 2% lidocaine. Epidural anaesthesia was performed at the first intercoccygeal space with 0.2 mg/kg of lidocaine and 0.17 mg/kg of xylazine. After 15 min, Received: 14 July 2021 bilateral laparoscopic ovariectomy was performed. Heart rate, respiratory rate, rectal temperature, Accepted: 16 August 2021 invasive arterial blood pressure, degree of analgesia, sedation and ataxia were evaluated during Published: 17 August 2021 surgery. The laparoscopic ovariectomy was successfully completed in all animals. Sedation and analgesia were considered satisfactory in six out of the eight mules. In conclusion, caudal epidural Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in block allowed surgery to be easily completed in six out of eight. The animals did not show any signs published maps and institutional affil- of discomfort associated with nociception and were mostly calm during the procedures, however iations. additional studies are needed to establish epidural doses of xylazine and lidocaine that result in reliable abdominal pain control in mules for standing ovariectomy. Keywords: epidural anaesthesia; laparoscopy; mule mares; ovariectomy; pain control; sedation Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and 1. Introduction conditions of the Creative Commons Mule (Equus mulus), interspecific hybrids between a male donkey and a female Attribution (CC BY) license (https:// horse, combine features from both donkey and horse, leading to great diversity in size, creativecommons.org/licenses/by/ temperament and body type [1]. 4.0/). Animals 2021, 11, 2419. https://doi.org/10.3390/ani11082419 https://www.mdpi.com/journal/animals Animals 2021, 11, 2419 2 of 11 Although mule mares are sterile, they show a rather variable oestrus [2]. During this period, they may present typical unwanted modification of behaviour such as reluctance to work, aggression, kicking and biting [3]. Bilateral ovariectomy in mule mares is an elective procedure performed, as in equine mares, to suppress unwanted oestrus behaviour and to decrease visceral pain occurring during oestrus [4–6]. In addition, it is performed in order to improve work performance. The surgery may be carried out by laparotomy under general anaesthesia, or by laparoscopy which can be performed either in the standing sedated horse or in dorsal recumbency under general anaesthesia [7]. An advantage of standing sedation over general anaesthesia is the decreased risk of mortality [8]. The benefits of standing laparoscopy, compared to laparotomy performed under gen- eral anaesthesia, include lower costs, direct visualization of abdominal viscera, secure haemostasis, tension-free manipulation of the ovaries and smaller flank incisions. These ad- vantages reduce complications and hospitalization time associated with ovariectomy [9,10]. To provide a good level of analgesia with no response to surgical stimulus, the use of a combination of sedative and analgesic drugs associated with locoregional technique is required [10]. In general, local analgesia is achieved by paravertebral anaesthesia and/or by the subcutaneous, intramuscular and subperitoneal administration of local anaesthetics bordering the dorso-caudal aspect of the last rib and the ventro-lateral aspect of the lumbar transverse processes. The analgesia is potentiated by local anaesthetic infiltration of the ovarian pedicles or by simple topical anaesthetic application to the ovary, which might reduce the risk of trauma caused by the needle which in turn can cause haemorrhage thereafter [11,12]. In horses, the epidural space is accessible at the lumbosacral joint (cranial epidural) or caudal to the sacrum (caudal epidural). The caudal epidural approach (sacrococcygeal or Co1–Co2 space) is preferable, as it is not only easier or safer to perform and reduces the potential for nerve damage with respect to subarachnoid anaesthesia. Indeed, the caudal approach reduce the risk of inadvertent injection in the subarachnoid space as well as the risk of motor blockade of the pelvic limbs, compared to the cranial approach. Caudal epidural anaesthesia is used to desensitize the coccygeal and last two or three sacral nerves, providing sensory loss of the anus, rectum, perineum, vulva, vagina, urethra, and bladder with the aim of inducing regional anaesthesia for surgery without losing motor function of the hind limbs [13]. This technique is also used to perform standing surgery using the flank approach to the abdomen [14,15]. The injection of drugs is performed into the extradural space, i.e., outside the dura mater, but underneath the ligamentum flavum [16]. Complications are represented by failure to achieve a good analgesia, ataxia or recumbency due to overdose and motor and sympathetic blockage [16,17]. A combination of a local anaesthetic drug with an alpha2-adrenergic agonist or an opioid is the most popular option, as this combination extends the duration of the epidural anaesthesia or analgesia in horses [18–20]. The purpose of this study was to determine the analgesic efficacy and safety of caudal epidural lidocaine-xylazine in standing mules undergoing elective bilateral laparoscopic ovariectomy. 2. Materials and Methods The study was approved by the Bioethics Committee of the Department of Veterinary Sciences of the University of Messina and followed the Good Scientific Practice Guide- lines and adhered to European legislation, EU Directive 2010/63 (Ethical approval code N. 050/2021). Eight healthy adult mule mares, American Society of Anaesthesiologists (ASA) phys- ical status 1, aged 3 to 7 years, with a body weight ranging between 380–450 kg, were included in the study. Exclusion criteria included ASA physical status ≥2, intractable be- haviour, neurological or neuromuscular disease and skin infection at the site of the surgery or that of the epidural anaesthesia. Mules had free access to water, but food was withheld Animals 2021, 11, 2419 3 of 11 for 16 h prior to surgery. Sodium benzylpenicillin [30,000 U/kg, intramuscularly (IM)] in combination with gentamicin [6.6 mg/kg intravenously (IV)] and flunixin meglumine (1.1 mg/kg, IV) were administered preoperatively. Body weight estimated on the bases of the body length and chest girth of the mules [21]. The mares were placed in a stock and the tails were wrapped (Benda PoweFlex, Alcyon, Italy). No other physical restraint was provided. The animals were sedated by the same expert anaesthetist and the laparoscopic ovariectomy was performed on a farm where the animals were housed. Any eventual disturbing factors which could have contributed to a sudden recovery from sedation were avoided because the stock was located at an adequate distance from the boxes. Before administering any drug, baseline rectal temper- ature (RT, ◦C), heart rate (HR, beats/min), and respiratory rate (RR, breaths/min) were recorded. HR was measured